Induction heating apparatus



INDUCTION HEATING APPARATUS Filed June 25, 1946 High Flequem Generator 9 J LJ {9 9 .12. g 31 5 23' 1 L Isl:- 4/ 4/ 4/ 17 Fiyb.

WITNESSES: INVENTOR i'au zgrd M. W/zanfi ATTORNEY Patented July 19, 1949 UNITED STATES PATENT OFFICE INDUCTION HEATING APPARATUS Edward M. Wharif, Baltimore, Md., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 25, 1946, Serial No. 679,142

2 Claims.

This invention relates to the induction heating of metal articles, or substances, of irregular shape which are moved by a conveyor or turn table through a rapidly alternating magnetic field. Generally, such work or charges are difiicult to heat in a uniform or desired manner because the magnetic flux lines tend to pass into the article in manners determined by the conductivity. permeability and disposition of the article with respect to the field, whereas the part of the article which it is desired to heat may be unre ated to the manner in which the field lines are aifected.

An object of my invention is to provide an induction heating system of a type described for controllably heating articles or pieces of work so as to concentrate the heat in desired parts of the articles, or workpieces.

A furt er ob ect of my invention is to provide an induction heating system which comprises a conveyor for successively moving a plurality of articles. or workpieces, through a magnetic field, the system having means for concentrating the heat in particular parts of the articles as they move through the field.

A further object of my invention is to provide a conveyor heating system of the type described, using induction heating, in which the means which directs the heat to localized portions of the travelling articles is quickly and easily changed so that various types and kinds of articles, or workpieces, can be readily heated. These changes can be effected by an unskilled operator without difllculty.

Features, ob ects, and innovations of my invention, in addition to the foregoing, will be discernible from the following simplified disclosure of a preferred form to which, however, I am not limited. This disclosure, disclosing the principles of my invention, comprises the following description and drawing which are to be considered in conjunction.

In the drawing:

Figure 1 is a diagrammatic plan view, with parts broken away, of an arrangement in accordance with my invention;

Fig. 2 is a diagrammatic sectional view substantially along the line 11-11 of Fig. 1;

Figs. 3 and 4 are a plan view and an elevational view, respectively, of a fleld-afiecting element used in my invention; and

Figs. 5 and 6 are views, corresponding to Figs. 3 and 4, of a modified form of field-affecting element.

Referring to the drawing, the work-receiving conveyor is illustrated as a turntable l driven by any suitable means, either step-by-step or continuously. Preferably, the turntable is of wood, asbestos, or other insulating material. However, the table can be located far enough from the field of the coil so that it can be made of metal. The circumferential portion of the turntable is provided with a plurality of spaced heating stations 3, each comprising a work-holding means, indicated in its entirety in Fig. 2 by the reference numeral 5, for holding a workpiece 1. Each work-holding means comprises a shaft 9 rotatably supported by the turntable. To this end, a thrust and guide bearing ll may be provided in the turntable and a guide bearing l3 under the guide bearing H. The guide bearing 13 may be supported in a bracket l5 carried by the turntable. The portion of the shaft 9, which is between the bearings, has fixed thereto a pulley I! which may be faced with leather, if desired. The shaft 9 has a portion, extending above the turntable, that carries a non-metallic narrow cylindrical fixture I 9.

The top of the fixture l9 has a seat with a central portion shaped to receive a workpiece 'l and an outer portion providing a seat for a fieldafiecting means 2|. The field-affecting means 2| comprises a metal plate, or disc, 23 having a central opening 25 shaped to conform to the part of the workpiece 1 which is to be controllably inductively heated.

The field-affecting means at the various heating stations are preferably of the same outer diameter and small enough to pass within but close to an arcuate elongated induction heatingcoil 21 which has turned-up ends to permit the workpiece to pass longitudinally into the central part of the heating-coil, which is permeated by magnetic flux when the heating-coil is energized with high frequency current from a high-frequency tube-oscillator generator 29. The coil comprises several turns of hollow tubing through which water may be passed for cooling. The number of turns of the coil can be determined by the portions of the workpieces to be heated.

Each field-afiecting means is preferably of copper which has a low resistivity or high conductivity for electricity. A cut or slot 3| is provided in each disc, which extends in a general radial direction from the periphery of the inner opening of the disc to the outer periphery of the disc. The disc acts as a secondary heating-coil or as a coupling from the long-curved heatingcoil 21 to the workpieces inside the heating-coil. The magnetic flux of the heating-coil generates body of the associated can. For such purpose.

the discs 23 are relatively narrow, and each 10- cated so as to surround the'partsof the can that are to be soldered together.

By changing the inner contour the disc, a V

difi'erently shaped can can be: treated. and in Fig. 5, I show another disc 35 having a. larger inner opening 31 and a slot 39. Theexterior periphery on this disc is the same as that of the disc 23. v

Each of the discs, irrespectiveof its shape, is provided with a pair ofpins M; The pins are arranged the same way on all the discs. Each seat of the fixtures H! has a pair of holes for receiving the pins of a disc, so that discs canbe easily'interchanged or different discs substituted. Consequently, workpieces of various sizes'and shapes can be heat-treated in the apparatus described, Without changing the induction heatingc'oilor controls 'on the high-frequency tube-oscillator generator. 1

It is sometimes desirable to: rotate-the articles being heated as they-pass along the induction heating-coil. To this end, a fixed arcuate abutment 43 is provided which'is engaged by the pulleys II as they pass through the heating-coil. The friction between each pulleyand the abutment-causes rotation of the work fixture, together with the workpiece and split disc which each fixture supports. By predetermining the length of the abutment 43, the workpieces will be rotated during any desired portion of its path of travel inside of the heating-coil. This is indicated in Fig. I by: terminating the end of the abutment 43 shortof'the exit end of the-heating-coil 2T.

While I have described my invention in" forms which I'now consider'to embrace preferred features, it is' obviousthat the principles of my invention can be applied to-other forms and modifications;

l? claim a'smy invention: 1. An induction. heating means comprising an elongated induction. heating-coil; for producing .4 a pulsating magnetic field, a conveyor means having a work-receiving station for receiving work to be carried into and out of said field, said conveyor means being constructed and arranged to move said station through said field in a predetermined direction, a removable secondary coil at said station for determining the field passing to;a part of the lVOlk as the conveyor moves said Work, cooperating positioning means comprising parts on said secondary coi1 and said station for locating and maintaining said secondary coil. in predetermined magnetic coupling relation withv respect to the associated work as both arenroved through said field, and means for rotating saidstation and said secondary coil with respect to said induction heating-coil as thestation and' secondary coil are moved by said conveyor means through said heating-coil.

2. An elongated induction heating-coil, a conveyor means having a plurality of spaced heatin'g stations, saidheating coil and said conveyor means being constructed and arranged so that saidstations can be successively moved along the sides of said coil with a plurality of stations inside the coil,'each of said stations comprising a distinct seat having a Work-receiving point, each seat also'having means for removably receiving a slotted and apertured metallic plate about its work-receiving point, means for rotating 2. seat and' its plate as said conveyor means moves them through said coil, said seats and said plates having cooperative' positioning means for locating a plate on its associated seat and maintaining it on said seat during move ment of said conveyor means and rotation of said seats. i

EDWARD M. WHARE E'.

REFERENCES CITED .The following references are of ,record in. the file of. this patent:

UNITED STATES PATENTS OTHER REFERENCES 'Roberd's, Coupling Methods for Induction Heating, Electronic Industries, April 1944, pages 180, 182, 

